Nonequilibrium stochastic processes: Time dependence of entropy flux and entropy production

Based on the Fokker-Planck and the entropy balance equations we have studied the relaxation of a dissipative dynamical system driven by external Ornstein-Uhlenbeck noise processes in absence and presence of nonequilibrium constraint in terms of the thermodynamically inspired quantities like entropy flux and entropy production. The interplay of nonequilibrium constraint, dissipation and noise reveals some interesting extremal nature in the time dependence of entropy flux and entropy production.Comment: RevTex, 17 pages, 9 figures. To appear in Phys. Rev.

Fluctuation-dissipation relationship in chaotic dynamics

We consider a general N-degree-of-freedom dissipative system which admits of chaotic behaviour. Based on a Fokker-Planck description associated with the dynamics we establish that the drift and the diffusion coefficients can be related through a set of stochastic parameters which characterize the steady state of the dynamical system in a way similar to fluctuation-dissipation relation in non-equilibrium statistical mechanics. The proposed relationship is verified by numerical experiments on a driven double well system.Comment: Revtex, 23 pages, 2 figure

Environment-induced dynamical chaos

We examine the interplay of nonlinearity of a dynamical system and thermal fluctuation of its environment in the ``physical limit'' of small damping and slow diffusion in a semiclassical context and show that the trajectories of c-number variables exhibit dynamical chaos due to the thermal fluctuations of the bath.Comment: Revtex, 4 pages and 4 figure

Generalized quantum Fokker-Planck, diffusion and Smoluchowski equations with true probability distribution functions

Traditionally, the quantum Brownian motion is described by Fokker-Planck or diffusion equations in terms of quasi-probability distribution functions, e.g., Wigner functions. These often become singular or negative in the full quantum regime. In this paper a simple approach to non-Markovian theory of quantum Brownian motion using {\it true probability distribution functions} is presented. Based on an initial coherent state representation of the bath oscillators and an equilibrium canonical distribution of the quantum mechanical mean values of their co-ordinates and momenta we derive a generalized quantum Langevin equation in $c$-numbers and show that the latter is amenable to a theoretical analysis in terms of the classical theory of non-Markovian dynamics. The corresponding Fokker-Planck, diffusion and the Smoluchowski equations are the {\it exact} quantum analogues of their classical counterparts. The present work is {\it independent} of path integral techniques. The theory as developed here is a natural extension of its classical version and is valid for arbitrary temperature and friction (Smoluchowski equation being considered in the overdamped limit).Comment: RevTex, 16 pages, 7 figures, To appear in Physical Review E (minor revision

Case Report- Spontaneous rupture of urinary bladder in puerperium

We report a case of spontaneous rupture of urinary bladder during normal vaginal delivery in a primigravida, who presented with huge ascites, oliguria and renal failure 3 days after delivery. Abdominal paracentesis and CT cystography diagnosed intraperitoneal rupture of urinary bladder. The rent was repaired in layers. In the follow-up cystoscopy and the cystography showed the lesion healed completely. This is totally preventable condition if adequate precaution is taken in the form of evacuating the bladder before the patient goes to second stage of labour

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Case Report - Recurrent rhinosporidiosis of male urethra

Rhinosporidiosis is a chronic granulomatous disease caused by a fungus, Rhinisporidium seeberi . Though the favored site is the nasal mucosa, urethral involvement does occur in this disease, only a few cases are reported in the literature and they are mostly from India. Here we report a case of recurrent urethral rhinosporidiosis, presenting as a protruding mass from the urethral orifice during voiding

Molecular Recognition in Beta-lactams: the crystal packing in 4-sulfonyl Beta-lactams

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